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Journal of Plant Diseases and Protection - The effects of ethanolic extracts (20 % per fresh weight (Fw) or 6 % per dry weight) of 20 different plant species were tested against late blight...  相似文献   
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There are two main approaches to diagnosing infections by Chlamydia and Chlamydophila spp. in mammals and birds. The first involves the direct detection of the agent in tissue or swab samples, while the second involves the serological screening of blood samples for the presence of anti-chlamydial antibodies. Ultimately, the test that is used is dependent on the types of samples that are submitted to the diagnostic laboratory for analysis. The present paper gives an overview on methodologies and technologies used currently in diagnosis of chlamydial infections with emphasis on recently developed tests. The performance characteristics of individual methods, such as the detection of antigen in smears and in pathological samples, the isolation of the pathogen, various antibody detection tests and DNA-based methods utilising conventional and real-time PCR, as well as DNA microarray technology are assessed, and specific advantages and drawbacks are discussed. Further, a combination of a specific real-time PCR assay and a microarray test for chlamydiae is proposed as an alternative reference standard to isolation by cell culture.  相似文献   
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BACKGROUND: The most important pest of olive orchards worldwide is the olive fruit fly Bactrocera oleae (Gmelin). Its control in Greece has been based on organophosphates (OPs), but their intense use has led to the development of resistance. A test previously developed to monitor the trait may not be as robust as originally thought. The pyrethroid alpha-cypermethrin has recently been registered for bait sprays, as an alternative to OPs. RESULTS: The susceptibility of 20 B. oleae populations to alpha-cypermethrin was examined. Variation was observed in their response, with LD(50) ranging from 0.14 to 3.28 ng insect(-1) and resistance factors from 2.3 to 54.7. Resistance mechanisms were investigated. Cytochrome P450 monoxygenase activities showed an association with resistance. Sequences in the domain IIS4-IIS6 of the B. oleae para-type sodium channel were also analysed, but no resistance-associated mutations were identified. Finally, a novel diagnostic assay able to reliably monitor the frequency of the iAChE G488S resistance mutation was developed. CONCLUSION: This is the first attempt to evaluate the efficacy of alpha-cypermethrin against B. oleae from Greece. Data showed that it can be used effectively, but also highlighted the importance of continuous monitoring. The IIS4-IIS6 sodium channel region is the default area in which to look for resistance mutations if target-site resistance to pyrethroids arises. The application of the novel iAChE molecular diagnostic may facilitate the introduction of pyrethroids alongside OPs currently in use.  相似文献   
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BACKROUND: In Tetranychus urticae Koch, acetylcholinesterase insensitivity is often involved in organophosphate (OP) and carbamate (CARB) resistance. By combining toxicological, biochemical and molecular data from three reference laboratory and three OP selected strains (OP strains), the AChE1 mutations associated with resistance in T. urticae were characterised. RESULTS: The resistance ratios of the OP strains varied from 9 to 43 for pirimiphos‐methyl, from 78 to 586 for chlorpyrifos, from 8 to 333 for methomyl and from 137 to 4164 for dimethoate. The insecticide concentration needed to inhibit 50% of the AChE1 activity was, in the OP strains, at least 2.7, 55, 58 and 31 times higher for the OP pirimiphos‐methyl, chlorpyrifos oxon, paraoxon and omethoate respectively, and 87 times higher for the CARB carbaryl. By comparing the AChE1 sequence, four amino acid substitutions were detected in the OP strains: (1) F331W (Torpedo numbering) in all the three OP strains; (2) T280A found in the three OP strains but not in all clones; (3) G328A, found in two OP strains; (4) A201S found in only one OP strain. CONCLUSIONS: Four AChE1 mutations were found in resistant strains of T. urticae, and three of them, F331W, G328A and A201S, are possibly involved in resistance to OP and CARB insecticides. Among them, F331W is probably the most important and the most common in T. urticae. It can be easily detected by the diagnostic PCR‐RLFP assay developed in this study. Copyright © 2009 Society of Chemical Industry  相似文献   
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BACKGROUND: A major problem of crop protection in Crete, Greece, is the control of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) with chemical insecticides owing to the rapid development of resistance. The aim of this study was to investigate the establishment of resistance and the underlying mechanisms to major insecticide classes with classical bioassays and known biochemical resistance markers. RESULTS: During a 2005–2007 survey, 53 Q biotype populations were collected. Application history records showed extensive use of neonicotinoids, organophosphates, carbamates and pyrethroids. High resistance levels were identified in the majority of populations (>80%) for imidacloprid (RF: 38–1958×) and α‐cypermethrin (RF: 30–600×). Low resistance levels (RF < 12) were observed for pirimiphos‐methyl. A strong correlation between resistance to imidacloprid and the number of applications with neonicotinoids was observed. Significant correlations were observed between COE and P450‐dependent monoxygenase activity with resistance to α‐cypermethrin and imidacloprid respectively. A propoxur‐based AChE diagnostic test indicated that iAChE was widespread in most populations. Resistance levels for α‐cypermethrin were increased when compared with a previous survey (2002–2003). Differentiation of LC50 values between localities was observed for imidacloprid only. CONCLUSION: Bemisia tabaci resistance evolved differently in each of the three insecticides studied. Imidacloprid resistance seems less established and less persistent than α‐cypermethrin resistance. The low resistance levels for pirimiphos‐methyl suggest absence of cross‐resistance with other organophosphates or carbamates used. Copyright © 2008 Society of Chemical Industry  相似文献   
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Context

This study investigates post-fire natural regeneration of Aleppo pine (Pinus halepensis) forests at Ilia region (Peloponnesus, Greece) following the catastrophic fire of 2007.

Aims

The objective of this study is the prediction of P. halepensis post-fire regeneration at a regional scale through an integrated geographic information systems (GIS) model as a basis for post-fire management plans.

Methods

The model was developed in three interconnected stages: (1) field data collection, (2) development of two prediction models (based on interpolation of field data and multi-criteria evaluation (MCE) that combined factors known to affect regeneration), and (3) combination of applied models using Bayesian statistics.

Results

Post-fire pine regeneration presented high variation among the studied plots. Redundancy analysis revealed the positive effect of fallen branches and a negative correlation with altitude. Both modeling approaches (geostatistical and MCE) predicted the post-fire pine regeneration with high accuracy. A very significant correlation (r?=?0.834, p?<?0.01) was found between the combined final model and the actual number of counted seedlings, illustrating that less than 10?% of the studied area corresponds to sites of very low post-fire pine regeneration.

Conclusions

The combination of GIS models increased the prediction success of different levels of pine regeneration. Low-altitude areas with low grass cover overlying tertiary deposits were proved the most suitable for pine regeneration, while stands developing on limestone proved least suitable. The proposed methodology provides management authorities with a sound tool to quickly assess Aleppo pine post-fire regeneration potential.  相似文献   
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